1. Field of the Invention
This invention relates to a method and a composition prepared according to said method. More specifically, this invention involves a method for enhancement in both the rate and completeness of discharge of electrostatographic imaging members comprising phthalocyanine pigments.
2. Description of Prior Art
The formation and development of images on the imaging surfaces of photoconductive materials by electrostatic means is well known. The best known of the commercial processes, more commonly known as xerography, involves forming a latent electrostatic image on the imaging surface of an imaging layer by first uniformly electrostatically charging the surface of the imaging layer in the dark, followed by exposing this electrostatically charged surface to a light and shadow image. The light struck areas of the imaging layer are thus rendered relatively conductive and the electrostatic charge selectively dissipated in these irradiated areas. After the photoconductor is exposed, the latent image on this image bearing surface is rendered visible by development with finely divided colored electroscopic materials, known in the art as "toner".
In order to be able to develop the latent image on the photoconductive insulating layer, the difference between the potential in the exposed and unexposed areas of this layer (this difference hereinafter referred to as the "contrast potential") must be sufficient to permit the electroscopic toner particles to discriminate between these two areas, and thus, be preferentially attracted to only one of them. Subsequent to development and transfer of the image, the imaging surface of the photoconductive insulating layer is cleansed of toner residues and its surface potential neutralized prior to recycling. Under ideal conditions, the sensitizing surface charge is substantially completely discharged between cycles. In the event of a failure to completely dissipate the surface potential, due to, for example, trapping of charge carriers in the bulk of the photoconductive insulating layer, the charge acceptance of the photoconductive insulating layer in successive copying cycles will be appreciably reduced, thus, reducing the maximum attainable contrast potential.
The inherent insulating properties of the materials used in preparation of photoconductive insulating layers can also affect both the rate and completeness of discharge of a sensitizing surface charge. Where the photoconductive insulating layer comprises phthalocyanine pigments dispersed in an insulating binder, completeness of discharge is apparently time dependent. In the event that the cycling interval of the photoreceptor is too rapid to permit completeness of dissipation of a sensitizing surface charge, the residual charge remaining on and within the imaging layer will be relatively high and thus maximum attainable contrast potential will be reduced upon recycling.
Accordingly, it is the object of this invention to remove the above as well as related deficiencies in the prior art.
More specifically, it is the primary object of this invention to provide a method for enhancing the efficiency of phthalocyanine based photoreceptors in rapidly cycling electrostatographic imaging systems.
It is another object of this invention to provide a method for enhancing the completeness of photodischarge of an electrostatographic imaging member comprising phthalocyanine pigments.
It is yet another object of this invention to provide a method for enhancing the rate of photodischarge of an electrostatographic imaging member comprising phthalocyanine pigments.
Still yet another object of this invention is to provide an electrostatographic imaging member having improved efficiency and completeness of photodischarge and an imaging process utilizing said imaging member.